The present invention relates to tire repair patches and more particularly to an improved tire repair patch for use either singularly or jointly with a tire repair plug for sealing a puncture of a vehicle tire.
Current tire repair patches are of two types, viz., small flexible patches of thin sheet rubber-like materials and larger stiffer patches, commonly referred to as boots, which taper from thick center portions to thin outer portions. In the current practice a puncture is sealed by adhesively bonding one surface of a repair patch to the inner surface of the tire without providing clearance between the patch and tire surface adjacent to the puncture.
Heretofore, repairs with tire patches have lacked the requisite durability and reliability for the severe service conditions tire repairs are commonly subjected to. Additionally, the high weight of the large fiber reinforced patch has caused tire imbalance and thumping noises in tires repaired therewith.
During constant speed driving, a rolling tire is deformed during each revolution thereof as it passes through the tire-to-road contact zone and further deforms during vehicle acceleration, braking, cornering and road impact.
By way of illustration of the severe service a repair patch is subjected to, approximately eight hundred thousand tire revolutions can occur during each one thousand miles of vehicle driving and a corresponding number of stress cycles will occur in a repair patch which is adhesively bonded to the tire. Heretofore, it has not been uncommon for tire repair patches to fail after several thousand miles of driving.
One factor contributing to the failure of repair patches is the current practice of bonding a patch to the portion of the tire adjacent to a puncture. As a result of this practice, patch stresses close to the puncture are substantially higher than patch stresses farther from the puncture because tire deflections in the vicinity of the puncture, and hence the portion of the patch bonded thereto, are greater than the undamaged portion of the tire farther from the puncture and portion of the patch bonded thereto.
Another contributing factor is that the compression of air within the tire and hysteresis losses of the tire produce large quantities of heat which are transferred to the patch, thereby raising the temperature of said patch with a consequent deleterious effect on the patch material.
Another contributing factor is the lack of clearance between the puncture and the patch adjacent to the puncture which exposes the patch to damage by the ends of broken steel reinforcing wires of radial ply tires.